2cents: Barring tune-up related issues.......When the engine stumbles and revs up and stumbles and revs at tempatures below 40 this is the first signs of the IAC failing but not enough to set off CEL.....OBD I Systems. OBDII's could be the same, however theOBDII should throw the light to have engine checked.
With issue on this post I would lean toward theengine temp sensor (NOT THE Temp Gauge sensor there are 2 temp sensors on the 3.0L 2002Ranger). As it is sensing temp ranges and atlower temps can fall outsideoperationalparameters.Bothof these units can be checked with a gooddigital meter, however you need the range specs for your model year,usually in a chilton or similar manual.

 

Try to visit www.carsinparts.nl fornew parts!

 

Thanks, Yeah I have changed the Iac, Fuel filter, ect, and iat sensors, I tried cyclinging the pump four times and no cjange. I cleaned the maf and I was told that the maf may be malfunctioning, so I shpuld uplug it and see how the engine reacted, well I unpluged the maf and the engine hesitated for a instand and ran exactly the same. I let the truck idle with the maf unplugged for te minutes and a cel never came on. lately it has been warmer, about 23 degrees and the truck fired instantly. any thoughts. I heard a bad tps could cause hard starting, but it only dose it when really cold.

 

It sounds like you've ruled out the possibility of fuel pressure bleeding off. If that's definitely not the problem, then there's another check you could try in the ECT sensor circuit....You've already changed the ECT sensor. Pull the plug and do a resistance check to see what it reads (make sure it's in a reasonable ohms range for the antifreeze temperature that you have, you may have boughta faulty one). With the ohms reading of the sensor in mind, reconnect the plug and go to the computer and disconnect the connector. Read the resistance on the two pins in the connector that go to the ECT sensor. (you should be able to find this pin-out diagram in Autozone.com's wiring diagrams for your vehicle). The resistance reading should only be very slightly different than the reading you took at the sensor. This checks out the wiring between the computer and the sensor.

Edit: Looks like pin 38 and 91 lead to the ECT sensor. Pins 39 and 91 lead to the ACT sensor if you want to do the same with that sensor. Double check my info though...

 

Get a multimeter and test your battery voltage. Just to rule that out.

 

Ok, Ill see if ican get a hold of one. I just replaced the battery in october when this started, it is rated at 800 cold cranking amps.

 

I heard that the computer may have a bad ground because I can unplugg the sensors and let it run for ten minutes or more and no cel. How long should it take for the cel to come on. I heard the ground foe the computer is behind the headlight, is that true?

 

Well. I finally Took the truck in to a mechanic to see what the problem was and what he discvered was that the person who tunned it up before I purchased it in occtober put plugs that were to cold for the engine. He says that is a common mistakes with ford vehicles done by some mechanics, hes seen it a few times. I hope this will help those of you who cant pin point the problem.
Thanks to all of you.
mike